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[2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-475c427f77bsm107646305e9.3.2025.10.23.09.16.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Oct 2025 09:16:01 -0700 (PDT) Message-ID: Date: Thu, 23 Oct 2025 18:16:00 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/1] mm/ksm: recover from memory failure on KSM page by migrating to healthy duplicate To: Long long Xia , linmiaohe@huawei.com, lance.yang@linux.dev Cc: markus.elfring@web.de, nao.horiguchi@gmail.com, akpm@linux-foundation.org, wangkefeng.wang@huawei.com, qiuxu.zhuo@intel.com, xu.xin16@zte.com.cn, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20251016101813.484565-1-xialonglong2025@163.com> <7e533422-1707-4fea-9350-0e832cf24a83@redhat.com> <122ef241-787d-4e8c-82cf-01ff318293a6@163.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 21.10.25 16:00, Long long Xia wrote: > Thanks for the reply. > > I do some simple tests. > I hope these findings are helpful for the community's review. > > 1.Test VM > Configuration > Hardware: x86_64 QEMU VM, 1 vCPU, 256MB RAM per guest > Kernel: 6.6.89 > > Testcase1: Single VM and enable KSM > > - VM Memory Usage: >   * RSS Total  = 275028 KB (268 MB) >   * RSS Anon   = 253656 KB (247 MB) >   * RSS File   = 21372 KB (20 MB) >   * RSS Shmem  = 0 KB (0 MB) > > a.Traverse the stable tree > b. pages on the chain > 2 chains detected > Chain #1: 51 duplicates, 12,956 pages (~51 MB) > Chain #2: 15 duplicates, 3,822 pages (~15 MB) > Average: 8,389 pages per chain > Sum: 16778 pages (64.6% of ksm_pages_sharing + ksm_pages_shared) > c. pages on the chain > Non-chain pages: 9,209 pages > d.chain_count = 2, not_chain_count = 4200 > e. > /sys/kernel/mm/ksm/ksm_pages_sharing = 21721 > /sys/kernel/mm/ksm/ksm_pages_shared = 4266 > /sys/kernel/mm/ksm/ksm_pages_unshared = 38098 > > > Testcase2: 10 VMs and enable KSM > a.Traverse the stable tree > b.Pages on the chain > 8 chains detected > Chain #1: 458 duplicates, 117,012 pages (~457 MB) > Chain #2: 150 duplicates, 38,231 pages (~149 MB) > Chain #3: 10 duplicates, 2,320 pages (~9 MB) > Chain #4: 8 duplicates, 1,814 pages (~7 MB) > Chain #5-8: 4, 3, 3, 2 duplicates (920, 720, 600, 260 pages) Thanks, so I assume the top candidates is mostly zeropages and stuff like that. Makes sense to me then, it would be great to add that as motivation to the cover letter! -- Cheers David / dhildenb